diff --git a/src/wp-includes/class-wp-widget-factory.php b/src/wp-includes/class-wp-widget-factory.php
index b72538336e..2fd4d9d60f 100644
--- a/src/wp-includes/class-wp-widget-factory.php
+++ b/src/wp-includes/class-wp-widget-factory.php
@@ -45,19 +45,6 @@ class WP_Widget_Factory {
 		self::__construct();
 	}
 
-	/**
-	 * Memory for the number of times unique class instances have been hashed.
-	 *
-	 * This can be eliminated in favor of straight spl_object_hash() when 5.3
-	 * is the minimum requirement for PHP.
-	 *
-	 * @since 4.6.0
-	 * @var array
-	 *
-	 * @see WP_Widget_Factory::hash_object()
-	 */
-	private $hashed_class_counts = array();
-
 	/**
 	 * Registers a widget subclass.
 	 *